Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false and idempotentHint=false, so the description adds value by clarifying that partial records are acceptable and duplicate supplements are allowed – practical consequences of the non-idempotent flag. It stops short of saying what happens on duplicate entry (dedupe vs. new row) or what the tool returns, which keeps it out of the top band.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, each doing a distinct job: what it creates, which fields can be deferred, and which sibling to use instead. The verb and resource are front-loaded with no redundant restatement of the title.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple 3-parameter creation tool with no output schema and 0% schema coverage, this is nearly sufficient: purpose, edge case, and routing are all covered. It does not describe the return value or how the created supplement appears in the stack, a minor gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has zero description coverage, so the description carries the load. It communicates that name/supplement is the core required element while dosage and timing are optional because they may be undecided – useful semantic framing that the bare schema does not give.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource ('Add a supplement to the supplement stack') immediately, and it explicitly distinguishes the boundary from the 'food or medications' case handled by add_intake. An agent can tell this apart from joiva_add_shopping_item or stackwell_create_supplement without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It names both the positive condition ('any supplement, even if timing or dose is not yet decided') and the exclusion ('Do not use for food or medications'), then points to the correct alternative (add_intake). That is explicit when-to-use and when-not-to-use guidance with a named sibling.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.